[0001] This invention relates to power saving in video display units, in particular computer
displays/monitors.
[0002] In order to minimise power consumption of desktop computers, a display power management
signalling (DPMS) standard has been defined by VESA (Video Electronics Standards Association).
This aims to provide a common definition and methodology in which the display controller
sends a signal to the display that enables it to enter various power management states.
Four states are defined, "ON", "STAND-BY", "SUSPEND" and "OFF". "ON" refers to the
state of a display when it is in full operation. "STAND-BY" is an operating state
of minimal power reduction and with the shortest recovery time. "SUSPEND" refers to
a level of power management in which a substantial power reduction is achieved by
the display. A longer recovery time from this state is permitted than from the Stand-by
state. "OFF" indicates that the display is consuming the lowest level of power and
is non-operational. Normally a monitor in the DPMS OFF state consumes a few watts,
typically 3-5W. This consumption is necessary for "watching" the sync signals and
to make automatic "wake-up" possible. The present invention is, however, aimed at
providing means whereby the power consumption in the DPMS OFF mode is reduced to almost
zero, but the display can still be "woken up" from this mode when the sync pulses
are reapplied, this being achieved in a manner which is such that a number of somewhat
contradictory requirements are fulfilled. The requirements are
(i) that the sync inputs must be fully TTL-compatible, in order to ensure no overloading,
(ii) that there is full DPMS compatibility ie lust wake up even if just one of the
sync signals is active, with a worst-case duty cycle and polarity and
(iii) that this is achieved at moderate cost.
[0003] In GB 2264848 (ICL Personal Systems Oy) there is described a video display with remote
power switching. The video display unit has a built-in power supply and at least one
electrically controllable power switch for connecting mains voltage to the power supply.
A control circuit closes and opens the power switch, for switching on and off the
display unit, in response to the state of at least one video or deflection signal
received by the display unit, or a command received via a communications channel utilising
the signals of the video interface. By this means it is possible to automatically
switch on the display unit at the same time as the control unit (processor) is started.
In GB 2264848 this is achieved by rectifying at least one video or deflection signal,
charging a capacitor with the rectified signal and generating a start-up current pulse
from the capacitor. The pulse is supplied to the power switch, which when closed connects
mains power to the power supply. In other words, power for the switching is taken
from the sync signals, rectified, voltage doubled and applied to solid state relays
comprising the switch. Whilst this is simple in principle there are difficulties associated
with it. If the duty cycle of the syncs is low, the voltage doubler will take a long
time to charge. The solid state relays need to be very sensitive and in any event
they are expensive.
[0004] In EP A2 0709764, there is disclosed a power supply system, including a source control
circuit for operating a CRT display unit, which is capable of reducing power consumption
during an interruption of an external input signal given to the power supply system.
A holding circuit of a power control circuit is operable in response to such an interruption
to de-energise the source control circuit and is put into a self-holding state to
maintain a stop mode of the source control circuit, until the external input signal
is received again. The circuitry described enables the electric power to be reduced
to the order of 5 watts.
[0005] In DE Al 195 25 439, there is disclosed another energy-saving circuit for a display
apparatus, which controls turn on and/or off of an AC voltage supply and without the
need for an auxiliary power supply. This arrangement is such that the electric power
is reduced to below 1 watt.
[0006] The present invention aims to achieve automatic awakening from the DPMS OFF mode
in an alternative and cost-advantageous manner, and which permits almost zero power
consumption in that mode.
[0007] According to the present invention there is provided a video display unit comprising
a built-in power supply including electronically-controllable switch means, and control
means responsive to the presence of at least one active video or deflection signal
received by the display unit to switch on the display unit by appropriate control
of the switch means, the switch means being controlled in response to power extracted
from the at least one active signal, and the control means including peak sensing
circuits for extracting power from the at least one signal, said peak sensing circuits
comprising a respective diode/capacitor combination for each video or deflection signal,
and ac sensing circuits for detecting if the at least one signal is active or not,
characterised in that the ac sensing circuits comprise a respective capacitor/diodes
combination for each video or deflection signal.
[0008] Embodiments of the invention will now be described with reference to the accompanying
drawings, in which:
[0009] Figure 1 illustrates a prior art arrangement.
[0010] Figure 2 illustrates a simplified diagram of switched mode power supply SMPS corresponding
to supply 5 of Figure 1
[0011] Figure 3 illustrates, schematically, wake-up circuitry of the present invention in
combination with an SMPS and other ancillary elements.
[0012] Figure 4 illustrates a specific embodiment of wake-up circuitry of Figure 3 in more
detail.
[0013] Figure 5 illustrates another specific embodiment of wake-up circuitry of Figure 3
in more detail.
[0014] Referring firstly to Figure 1, which illustrates the known arrangement disclosed
in GB 2264848, a circuit for switching on and off a display (not shown) comprises
a power supply unit 5 connected via an electrically controllable power switch 4, a
fuse 3, a mains filter 1 and a mains connection 2 to an AC mains voltage eg 220 or
110V. The power switch 4 is controlled electrically by a signal Is and may be any
electronic or electro-mechanical switch meeting the electrical specification. As illustrated
separate solid state relays SSR1 and SSR2 are employed. A manual power switch S1 is
indicated in parallel with switch 4 for use in case of failure of switch 4. When switch
4 is switched on by control current Is, mains voltage is connected to the power supply
5, which generates the various operating voltages required in the video display unit
and represented commonly by the single voltage Ucc. Circuit 7 is a start-up and holding
circuit with an associated control unit CPU 6. Operating voltage is supplied by the
power supply 5 to circuit 7 and a control unit 6, which latter monitors the deflection
signal lines HSYNC and VSYNC and generates an operation enable signal ENABLE for circuit
7 when the deflection signals are present. The ENABLE signal actuates a hold current
circuit 7C so that it enables the passage of a hold current I
H from power supply 5 to a driver 7B, for the power switch 4, which derives drive current
I
S from the hold current I
H. When the control unit 6 detects the absence of the deflection signals, it eliminates
the signal ENABLE after a predetermined delay. Due to the absence of the signal ENABLE,
hold current circuit 7C blocks the passage of I
H to driver 7B, hence I
S ceases and power switch 4 is turned off (opened) and the supply 5 disconnected from
the mains voltage. Thus, there are no operating voltages in circuit 7 and control
unit 6, which cannot therefore monitor the deflection signals when the power switch
4 is open. The energy required to switch on the display unit is derived directly from
the deflection signals when they reappear.
[0015] For this purpose circuit 7 comprises rectifier diodes D1 and D2 for the half-wave
rectification of the deflection signals HSYNC and VSYNC respectively and for charging
capacitor C1 by the rectified signals. As the voltage level of the deflection signals
is relatively low, a voltage up-converter, such as a voltage doubler 7A, is provided
in order to get a sufficient voltage level for the subsequent circuits. The energy
level charged in the storage capacitor C1 is monitored by a comparator circuit, in
driver circuit 7B, which outputs the current pulse I
S for closing the power witch 4.
[0016] The power supply unit 5 may be comprised by a built-in switched mode power supply
SMPS as illustrated schematically in Figure 2. Apart from switch (transistor) 22 this
is commonly used in present day monitors. The SMPS comprises a bridge rectifier 20
which charges a tank capacitor 21. Transistor 22 delivers start-up power to the SMPS
controller 23, which rapidly opens and closes electronic switch 24. The precise timing
of this is controlled so as to drive the transformer 25 correctly, ie such that transformer
25 delivers correct secondary DC voltages at all tiles, in spite of varying secondary
loads. Figure 2 is only a schematic illustration and omits various rectifying diodes
and capacitors on the secondary side of the transformer, which in reality has several
different windings, rather than just one primary and one secondary as illustrated.
Transistor 22 is not provided in the SMPS for all monitors, it is however necessary
for the wake-up circuitry of the present invention and must be added if not already
present as it is required for switching off the start-up power supply to controller
23, as will be appreciated from the following.
[0017] In the known arrangement disclosed in GB 2264848, the sync signals are employed to
cause switch 4 to be closed in a substantially direct manner ie they are rectified,
voltage doubled and resultant pulses applied to relays in order to cause closure of
a switch. The present invention achieves the same effect but in a different and somewhat
indirect manner, which is able to operate with worst case scenario sync signals, and
switch on the monitor even when the latter is provided with lower power levels than
hitherto in the DPMS "OFF" mode, referred to hereinafter as near-zero watts. Hence
the proposed switching solutions results in even more power efficient (power saving)
monitors than hitherto.
[0018] The present invention achieves this, in part, by use of an optocoupler ie the sync
signals are used to drive a light emitting device and the emitted light is detected,
the output signal of the detector being used to achieve the switching.
[0019] In Figure 3, which uses the same reference numerals as Figures 1 and 2 where appropriate,
the optocoupler is an integrated circuit 32 which includes an LED 10 and a photodetector
11. The elements of the circuit coupled to the LED 10 and comprising substantially
the left half of the circuit 7 are not mains connected. This left half of the circuit
must activate the optocoupler 32 when one or both sync signals (Hsync, Vsync) are
active. The peak sensing circuits 30, comprised by diode Dxl and capacitor Cx3 and
diode Dx2 and capacitor Cx3 of the specific embodiment illustrated in Figure 4, can
extract enough power from the sync signals to drive the optocoupler, but they cannot
distinguish between an active sync signal and one that is inactive and high. AC-sensing
circuits 31, comprised by capacitor Cx1 and diodes Dx4 and Dx5, or capacitor Cx2 and
diodes Dx6 and Dx7, in Figure 4, can recognise an active sync signal correctly, but
they cannot extract enough power for the optocoupler if the sync signal is weak. Thus
both types are needed; the peak-sensing circuits 30 deliver the power, and the AC-sensing
circuits 31 open switch 33 (transistor Tx2 in Figure 4) at active sync signals, in
order to cause the LED 10 to emit light when the sync signals are active.
[0020] If an external sync driver, ie the drivers producing the sync signals Hsync and Vsync,
is as weak as worst-case TTL specifications allow, then the optocoupler will nevertheless
be driven safely, but a sync signal may be overloaded in the sense that it becomes
too poor for other users in the monitor. This is of no consequence provided that the
overloading is removed when the monitor has woken up. This overload removal can be
achieved by means of diode Dx3 and transistor Tx1 of Figure 4 as described in greater
detail hereinafter.
[0021] As is apparent from Figure 3, the output of the photodetector 11 is applied to a
mains connected control block 34 which is coupled to SMPS 5. Block 34 is supplied
from the tank capacitor 21 and controls the transistor/switch 22 and the SMPS 23.
As in Figure 1, block 7C represents the circuits that remove the loading of the sync
signals and is shown, for simplicity, as delivering just a single hold current l
H.
[0022] The elements of the specific embodiment illustrated in Figure 4 and so far not referred
to will now be discussed. As mentioned above, the sync signal overload can be removed
by means of diode Dx3 and transistor Txl. The "+5V" supply is the ordinary 5V supply
of the monitor and through diode Dx3 it replaces the currents from the peak-sensing
circuits when the monitor has been woken up. The "Heater" supply is the heater supply
for the monitor, which is also available when the monitor has been woken up. At DPMS
"ON", "STAND-BY" and "SUSPEND", the "Heater" supply is sufficiently higher than "+5V"
to ensure that Tx1 is supplying current through diode Dx8, thus replacing the currents
from the AC-sensing circuits. At DPMS "OFF", when the monitor's microprocessor 6 (Figure
3) discovers that both sync signals have gone inactive, the microprocessor turns off
the heater voltage and as a result the transistor Tx2 is rendered non-conductive,
ie switch Tx2 is closed. The monitor is turned off as a result of this, and when the
"+5V" supply drops, the microprocessor will eventually lose control and might turn
on the "Heater" supply again. However, when this happens the "Heater" supply can be
guaranteed to be (arranged to be) too close to "+5V" to be able to open Tx1.
[0023] The right half of the circuit of Figure 4, those elements connected to the photodetector
2, is the mains connected control block 34 of Figure 3 and is required to turn off
the monitor when the optocoupler is not active, and to turn on the monitor when the
optocoupler is active. Since the optocoupler 32 is mains connected the actual device
employed must be approved for mains application. The working power for this half of
the circuit is obtained from the positive terminal of the power supply's tank capacitor
21, as described above. This is around 300VDC at 230VAC, or 150VDC at 110VAC. This
power is present whenever the monitor is mains connected with its power switch on
(closed), Zener diode DZ1 limits the used voltage to 10V.
[0024] When the optocoupler is activated, transistor Tx3 quickly discharges capacitor Cx4.
It should be noted that the current through the optocoupler photodetector 11 may pull
the voltage over Zener diode DZxl down from 10V to almost 0, but that only speeds
up the discharging of capacitor Cx4 even further. As the charge current (through resistor
Rx10 when transistor Tx3 is off) is very much smaller than the discharge currents
(when Tx3 is on), the voltage over Cx4 will remain very close to 0 even when discharge
occurs at an extremely small duty cycle. It should be noted that Vsync pulses may
activate the optocoupler during a very small fraction of each vertical period. The
low voltage over Cx4 keeps transistor Tx4 turned off, so that the monitor's SMPS 5
can operate normally.
[0025] When both sync pulses are inactive, the optocoupler is inactive and Cx4 is charged,
so that transistor Tx4 starts to conduct. Diode Dx9 stops the SMPS controller 23 by
pulling down its connected pin (pin 1 in the case of UC3842), thus turning off the
monitor. As the normal power supply to the controller 23 is turned off too, the controller
23 could start to consume a lot of power, despite being turned off, from its start-up
supply circuit. This is prevented by diode Dx10, which turns off that supply when
Tx4 is conducting.
[0026] The main function of the filter comprised by resistor Rx11 and capacitor Cx5 is to
prevent spurious sync pulses and other kinds of noise from temporarily turning on
the monitor when it is on the DPMS "OFF" mode. Capacitor Cx4 is not able to provide
that filtering as it discharges too quickly when Tx3 is on, as described above.
[0027] Capacitors Cx4 and Cx5 also support the (optional)
override capability, defined in the DPMS standard.
[0028] If the monitor has been disconnected from the mains for about 7 minutes or more,
as a result of the power switch being turned off or the mains plug pulled out, then
the tank capacitor 21 will have discharged enough so that capacitors Cx4 and Cx5 are
also discharged to low voltages. If the monitor is then started without sync pulses,
transistor Tx4 will stay off long enough to give the microprocessor 6 time to discover
the absence of the sync pulses and set the override mode, which includes enabling
"Heaters so that the optocoupler is actuated and keeps the monitor on.
[0029] The components of Figure 4 may comprise the following, for example, for a typical
monitor (our designation 151p).
- 32
- H11AV1 or CNY17F-3 or other equivalent optocoupler with a current transfer ratio of
≥100% at IF= 10mA and approved for mains applications
- Tx1
- BC557B or equivalent SMD type
- Tx2-Tx4
- BC547B or equivalent sMD type
- Dx1-Dx2
- BAT42 (Schottky)
- Dx3-Dx10
- BZX55C 10 or equivalent
- Cx1-Cx3
- 100nF, plastic
- Cx4
- 22µF ± 20% ≥ 10V, electrolytic
- Cx5
- 47µF ± 20% ≥ 10V, electrolytic
- Rx1-Rx15
- Values as indicated in Figure 4, tolerance 5%. Power class 1/10W for Rx8, 1/16W for
all others
Rx14 and Rx15 rated for 200VDC
[0030] Using the above components with a 151p monitor, the power consumption in the DPMS
"OFF" mode was of the order of 0.25W at 230VAC, and less than 0.1W at 110VAC.
[0031] Essentially the same principal as employed in Figure 4 for our 151p monitor is also
applicable to other monitors. Figure 5 shows a circuit diagram for our 172p monitor,
which employs a different design philosophy. The circuit of Figure 5 has the following
additional components: IC2, transistor Tx5, zener diode DZx2, resistor Rx16, and resistor
Rx17. Transistor Tx1 is connected in a slightly different way in Figure 5 to that
in Figure 4.
[0032] In the 151p monitor, all of the other users of the sync pulses are such that they
do not present any load to the sync pulses when the monitor is off. However, in the
172p monitor and many other monitors, the sync pulses will be clamped down to unacceptable
levels when the monitor is off, unless a non-clamping buffer like 74LSxx or 74Fxx
is inserted. Buffers 74HCxx and 74HCTxx clamp in unpowered mode and cannot be used.
Hence the use of IC2, which comprises four AND gates in the case of a 74L508 and can
be connected as shown. The use of an additional IC2 is not essential, the same effect
could be achieved by appropriate redesign of the monitor's circuitry.
[0033] Together with the additional components, transistor Txl performs the same function
as transistor Txl in Figure 4, although for slightly different conditions. "+7V" is
the heater supply. At DPMS "ON", "STAND-BY" and "SUSPEND", both "+7V" and "+15V" are
on. At DPMS "OFF", when the monitor's processor discovers that both sync signals have
gone inactive, it turns off the "+7V", thus closing switch Tx2 (rendering transistor
Tx2 non-conductive) so that the LED is not powered. The monitor is turned off as a
consequence of this and when "+5V" drops, the microprocessor will eventually lose
control and might turn on "+7V" again. However, when that happens, the "+15V" supply
is guaranteed to be too low to open Txl via Tx5.
[0034] Whilst two specific circuit versions of the invention have been described above they
are essentially the same. The only differences are related to the circuitry of the
monitors with respect to which they have been described, namely our designations 151p
and 172p. The basic arrangement can of course be applied to other monitors.
[0035] These particular modifications are those appropriate to the particular types of monitors
in connection with which the present invention has been described.
[0036] The person skilled in the art and employing the invention with other monitors will
readily appreciate what if any modification it will be necessary to make to associated
circuitry in order to achieve the desired "almost zero" power state.
[0037] Typical components for the circuitry of Figure 5 are the same as indicated above
for Figure 4 except where previously mentioned, and as below: Tx5 is also a BC547B
(or equivalent SMD type), DZx2 in also a BZX55C10 or equivalent and Rx16 and Rx17
have the values indicated with a tolerance of 5%, and power class 1/16W.
[0038] As will be appreciated from the above, it is possible as a result of the described
circuitry to switch the power off/on via direct control of the SMPS controller 23.
Hence components like TRIACs and primary-side power-supply ICs are not needed, with
resultant cost saving possibilities. The manually operated switch S1 in Figure 3 will,
of course, always need to be in the closed state for this direct control, and will
only be in the illustrated open state when the monitor is entirely out of use.
[0039] Controlling the SMPS controller directly, as described above with reference to Figures
3, 4 and 5, saves a lot of money. The relays of GB 2264848, whether solid-state or
electromechanical relays, are expensive. Electromechanical relays of low or moderate
cost cannot withstand the large inrush currents at power up of monitors, and a solid-state
solution designed to survive safely at power-up would be even more expensive, whether
built with complete solid-state relays or TRIACs etc. It is also considered very unlikely
that a relay solution could be implemented without an extra "mini" power supply, because
of the very limited power that can be extracted from the sync signals.
[0040] In view of the DPMS standard requirements, the sync signal detection principle of
GB 2264848 is no longer usable. Using only a peak sensing circuit, as in GB 2264848,
was possible before the DPMS standard when it was acceptable to assume that inactive
signals should be kept at low level. The DPMS standard, now widely accepted and used,
allows inactive sync signals to be kept at either level. A peak sensing circuit cannot
distinguish between an active signal and one that is inactive and high. The present
near-zero watts implementation solves this problem by combining a peak sensing circuit,
which extracts the required power, with an AC sensing circuit. Furthermore, the near-zero
watts implementation is, unlike GB 2264848, fully TTL compatible. GB 2264848 assumes
that the sync-signal source can supply at least 1mA at 2.7V. However, many video boards
use a standard 74LS gate (eg 74LS04) as sync driver, and such a driver is only guaranteed
to source 0.4mA at 2.7V. The near-zero watts implementation is compatible with such
sources, as well as other TTL sources.
1. A video display unit comprising a built-in power supply (5) including electronically-controllable
switch means, (22,23,24), and control means (7) responsive to the presence of at least
one active video or deflection signal (Hsync, Vsync) received by the display unit
to switch on the display unit by appropriate control of the switch means (22,23,24),
the switch means being controlled in response to power extracted from the at least
one active signal, and the control means (7) including peak sensing circuits (30),
for extracting the power from the at least one signal, said peak sensing circuits
comprising a respective diode/ capacitor combination (Dx1, Cx3; Dx2, Cx3) for each
video or deflection signal, and ac sensing circuits (31) for detecting if the at least
one signal is active or not, characterised in that the ac sensing circuits comprise
a respective capacitor/diodes combination (Cx1, Dx4, Dx5; Cx2, Dx6, Dx7) for each
video or deflection signal.
2. A unit as claimed in Claim 1, characterised in that the peak sensing circuits (30)
are connected to a light emitting device (10) of an optocoupler (32) whose output
is employed to control the switch means, which light emitting device is in series
with the collector-emitter path of a first transistor (33;Tx2), and the ac sensing
circuits are connected to the base of the first transistor whereby the light emitting
device is driven for switching on the display unit when the at least one signal is
active and the first transistor is conductive.
3. A unit as claimed in claim 2, characterised in that following switching on of the
display unit by the power extracted from the at least one active signal, the light
emitting device (10) is driven by currents derived from a voltage supply (+5v) of
the monitor and the heater of the monitor rather than the at least one active signal,
whereby to avoid sync signal overload.
4. A unit as claimed 1, characterised in that the power supply (5) is a switched-mode
power supply (SMPS) including an SMPS controller (23) which is connectable to a start-up
power supply (21) via a first switch (22) of said switch means, the first switch (22)
connecting the start-up power supply to the SMPS controller (23) in response to the
power extracted when the at least one signal is active.
5. A unit as claimed in any one of the preceding claims, characterised in that the power
supply (5) is couplable to a mains supply (2) via a manually closable switch (S1),
and the control means (7) serves to switch on the display unit, when the manually-closable
switch is closed, in response to the presence of the at least one active signal.,
and in that the control means serves to switch off the display unit in response to
the absence of any active video or deflection signal.
6. A unit as claimed in Claim 5 as appendant to claim 4, characterised in that the start-up
power supply for the SMPS controller (23) is a tank capacitor (21) of the SMPS.
1. Videoanzeigegerät mit einem eingebauten Netzteil (5), das eine elektronisch steuerbare
Schaltvorrichtung (22, 23, 24) aufweist, und mit einer Steuereinrichtung (7), die
auf das Vorhandensein mindestens eines aktiven Video- oder Ablenkungs-Signals (Hsync,
Vsync) anspricht, das von dem Anzeigegerät empfangen wird, um das Anzeigegerät durch
entsprechende Steuerung der Schaltvorrichtung (22, 23, 24) anzuschalten, wobei die
Schaltvorrichtung in Abhängigkeit von der Energie gesteuert wird, die aus dem mindestens
einen aktiven Signal entnommen wird, und die Steuereinrichtung (7) Spitzenwert-Abtastschaltungen
(30) aufweist, um die Energie aus dem mindestens einen Signal zu entnehmen, wobei
die Spitzenwert- Abtastschaltungen eine entsprechende Dioden/Kondensator-Kombination
(Dx1, Cx3; Dx2, Cx3) für jedes Video- oderAblenksignal, sowie WS-Abtastschaltungen
(31) aufweist, die feststellen, ob das mindestens eine Signal aktiv ist oder nicht,
dadurch gekennzeichnet, daß die WS-Feststellschaltungen eine entsprechende Kondensator/Dioden-Kombination
(Cx1, Dx4, Dx5; Cx2, Dx6, Dx7) für jedes Video- oder Ablenksignal aufweisen.
2. Videoanzeigegerät nach Anspruch 1, dadurch gekennzeichnet, daß die Spitzenwert-Abtastschaltungen
(30) mit einer Licht emittierenden Vorrichtung (10) eines optischen Kopplers (32)
verbunden sind, dessen Ausgang zur Steuerung der Schaltvorrichtung verwendet wird,
daß die Licht emittierende Vorrichtung in Serie mit dem Kollektor-Emitter-Pfad eines
ersten Transistors (33; Tx2) geschaltet ist, und daß die WS-Abtastschaltungen mit
der Basis des ersten Transistors verbunden sind, wobei die Licht emittierende Vorrichtung
zum Anschalten des Anzeigegerätes angesteuert wird, wenn das mindestens eine Signal
aktiv und der erste Transistor stromleitend ist.
3. Videoanzeigegerät nach Anspruch 2, dadurch gekennzeichnet, daß im Anschluß an das
Einschalten des Anzeigegerätes durch die von dem mindestens einen aktiven Signal entnommene
Energie die Licht emittierende Vorrichtung (10) durch Ströme angesteuert wird, die
von einer Spannungsquelle (+5V) des Monitors und der Heizvorrichtung des Monitors
anstatt des mindestens einen aktiven Signals abgeleitet werden, um eine Synchronisiersignal-Überlastung
zu vermeiden.
4. Videoanzeigegerät nach Anspruch 1, dadurch gekennzeichnet, daß der Netzteil (5) ein
Schaltnetzteil (SMPS) ist, das ein SMPS-Steuergerät (23) aufweist, welches mit einem
Anlauf-Netzteil (21) über einen ersten Schalter (22) der Schaltvorrichtung verbindbar
ist, wobei der erste Schalter (22) das Anlauf-Netzteil mit dem SMPS-Steuergerät (23)
in Abhängigkeit von der Energie verbindet, die entnommen wird, wenn das mindestens
eine Signal aktiv ist.
5. Videoanzeigegerät nach einem der vorausgehenden Ansprüche, dadurch gekennzeichnet,
daß das Netzteil (5) mit einer Netzspeisequelle (2) über einen von Hand schließbaren
Schalter (S1) koppelbar ist, daß die Steuereinrichtung (7) zum Einschalten der Anzeigegerätes
dient, wenn der von Hand schließbare Schalter geschlossen ist, und zwar in Abhängigkeit
vom Vorhandensein des mindestens einen aktiven Signals, und daß die Steuereinrichtung
zum Abschalten des Anzeigegerätes in Abhängigkeit vom Fehlen eines aktiven Video-
oder Ablenksignals dient.
6. Videoanzeigegerät nach Anspruch 5 in Verbindung mit Anspruch 4, dadurch gekennzeichnet,
daß das Anlauf-Netzteil für das SMPS-Steuergerät (23) eine Kapazität (21) eines Oszillatorschwingkreises
der SMPS ist.
1. Unité d'affichage vidéo comprenant une alimentation incorporée (5) comprenant un moyen
de commutateur commandable électroniquement, (22, 23, 24), et un moyen de commande
(7) sensible à la présence d'au moins un signal vidéo ou de déviation actif (Hsync,
Vsync) reçu par l'unité d'affichage afin de mettre en marche l'unité d'affichage par
une commande appropriée du moyen de commutateur (22, 23, 24), le moyen de commutateur
étant commandé en réponse à une puissance extraite depuis le au moins un signal actif,
et le moyen de commande (7) comprenant des circuits de détection de crête (30) destinés
à extraire la puissance depuis le au moins un signal, lesdits circuits de détection
de crête comprenant une combinaison de diode/condensateur respective (Dx1, Cx3 ; Dx2,
Cx3) pour chaque signal vidéo ou de déviation, et des circuits de détection de courant
alternatif (31) destinés à détecter si le au moins un signal est actif ou non, caractérisé
en ce que les circuits de détection de courant alternatif comprennent une combinaison
de condensateur/diodes respective (Cx1, Dx4, Dx5 ; Cx2, Dx6, Dx7) pour chaque signal
vidéo ou de déviation.
2. Unité selon la revendication 1, caractérisée en ce que les circuits de détection de
crête (30) sont reliés à un dispositif émettant de la lumière (10) d'un coupleur optique
(32) dont la sortie est utilisée pour commander le moyen de commutateur, lequel dispositif
d'émission de lumière est en série avec la ligne collecteur-émetteur d'un premier
transistor (33 ; Tx2), et les circuits de détection de courant alternatif sont reliés
à la base du premier transistor d'où il résulte que le dispositif d'émission de lumière
est attaqué pour mettre en marche l'unité d'affichage lorsque le au moins un signal
est actif et que le premier transistor est conducteur.
3. Unité selon la revendication 2, caractérisée en ce qu'après la mise en marche de l'unité
d'affichage par la puissance extraite depuis le au moins un signal actif, le dispositif
d'émission de lumière (10) est attaqué par des courants obtenus à partir d'une alimentation
en tension (+5 V) du moniteur et du circuit de chauffage du moniteur à la place du
au moins un signal actif, afin d'éviter ainsi la surcharge du signal de synchronisation.
4. Unité selon la revendication 1, caractérisée en ce que l'alimentation (5) est une
alimentation à découpage (SMPS) comprenant un contrôleur d'alimentation SMPS (23)
qui peut être relié à une alimentation de démarrage (21) par l'intermédiaire d'un
premier commutateur (22) dudit moyen de commutateur, le premier commutateur (22) reliant
l'alimentation de démarrage au contrôleur d'alimentation SMPS (23) en réponse à la
puissance extraite lorsque le au moins un signal est actif.
5. Unité selon l'une quelconque des revendications précédentes, caractérisée en ce que
l'alimentation (5) peut être reliée à une alimentation secteur (2) par l'intermédiaire
d'un commutateur à fermeture manuelle (S1), et le moyen de commande (7) sert à mettre
en marche l'unité d'affichage, lorsque le commutateur à fermeture manuelle est fermé,
en réponse à la présence du au moins un signal actif, et en ce que le moyen de commande
sert à mettre à l'arrêt l'unité d'affichage en réponse à l'absence d'un signal vidéo
ou de déviation actif quelconque.
6. Unité selon la revendication 5, lorsqu'elle dépend de la revendication 4, caractérisée
en ce que l'alimentation de démarrage pour le contrôleur d'alimentation SMPS (23)
est un condensateur d'accumulation (21) de la norme SMPS.